Blade fastening means of the aforementioned type as a rule are used for fastening rotor blades on a rotor of a turbomachine, such as a steam turbine, which rotor blades rotate at high speed during rotation of the rotor. As a result of the fast rotation of the rotor, the associated rotor blades are subjected to a high centrifugal force. The blade root of the blades is therefore exposed to high forces and is displaced by a high degree radially outwards in a slot on the blade holder. Furthermore, the blades are exposed to severe vibrational loads so that mechanical damage, material fatigue, and corrosion on the slot can occur, and a shifting movement of the blade root inside the slot can occur.
For fixing the blade root inside the slot, various solutions, such as metal wedges, spring rings or sealing pieces, are known. Metal wedges certainly create a locking of the associated blade root inside a slot both axially and radially, but with large blades it is difficult with such metal wedges for retaining forces to be adequately created in the radial direction during rotation of the blade. Disk springs create only radial retaining forces and require additional expenditure for locking in the longitudinal direction of the associated slot. Furthermore, time-consuming measurements are required for disk springs during installation. As sealing pieces, two parts must always be provided, the installation of which furthermore partially necessitates the machining of the parts by hand.